Feedback control is the elementary mechanism through which many systems, like electrical, mechanical, or biological system maintain their equilibrium. Feedback control may be defined as the use of various signals that are determined by comparing the actual values of the system variables to their desired values, as a means of a control system. At the present, boost type three phase rectifiers are increasingly used for industrial applications such as uninterruptible power supplies (UPS), battery chargers, motor drives. Also, such as MOSFET, IGBT are commonly used by semiconductors, operate in high frequency switching devices which are free to switch at frequencies much higher than the main frequency, allowing the controller whose dynamic response is very high. The efficient conversion of power is a problem in the modern world. The power factor, one of the most vital characteristics in the AC/DC power conversion, describes the efficiency and superiority of such process. The unity-value power factor converter does not introduce any alteration to the energy source and exploits performance of the power conversion. Many schemes and solutions that are available in the field of power factor correction (PFC) are presented in the work. The thesis shows a power factor correction for a class of three-phase boost rectifier. Here a full-bridge boost converter has been studied for power factor control, using output sliding mode control. The sliding mode control drives the output voltage to the preferred dc level in the existence of external disturbances and internal parameter uncertainties providing a value of power factor close to unity. The controlled converters is simulated and studied for the effectiveness of the proposed control algorithms and good consistency is achieved.
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